Originally Posted by Doc Olds

Both Diffs have drain plugs, so the synthetic diff lube can easily be drained and then refilled.

First remove the drain plug using a 3/8" drive socket wrench w/ short extension. While that is draining into a pan, remover the fill plug. Let them drain a good long while, and wipe off the drain plug. I also like to squirt in some clean gear lube when drained to sort of wash out any last residue, then put the drain plug back in. You do not need to use lock tight or teflon tape, I have never had the drain plug leak after snugged in place.

Then fill with synthetic 75W-90 up to the level of the fill plug, put the fill plug back in and snug.

The front spec capacity is 1.5 Qts (1.45L), rear is 2.1 Qts (2.0L) so to do both you will need to buy 4 Qts, and have some left over even if you do squirt in a bit for the wash out like described above.

I used Mobil One synthetic as it was on sale cheaper than the other brands.

There is another thread on T Case procedure.